ASTMangler: skip mangling Copyable dependents

Typically, a conformance that is dependent on a conformance to a marker
protocol never reaches this point in the compiler, where we're mangling
the metadata for an opaque return type.

But with the invertible protocols like Copyable, we do permit them, so
we should avoid mangling Copyable as that's generally ABI incompatible
with existing code.

resolves rdar://135310019

Author: kavon

lib/AST/ASTMangler.cpp

@@ -4201,6 +4201,12 @@ void ASTMangler::appendAnyProtocolConformance(
       conformance.getRequirement()->isMarkerProtocol())
     return;
 
+  // While all invertible protocols are marker protocols, do not mangle them for
+  // compatability reasons. See equivalent hack in `conformanceRequirementIndex`
+  // where only invertible protocols are unconditionally skipped.
+  if (conformance.getRequirement()->getInvertibleProtocolKind())
+    return;
+
   if (conformingType->isTypeParameter()) {
     assert(genericSig && "Need a generic signature to resolve conformance");
     auto path = genericSig->getConformancePath(conformingType,

test/Interpreter/moveonly_generics_opaque.swift

@@ -0,0 +1,29 @@
+// RUN: %target-run-simple-swift(-Xfrontend -disable-availability-checking) | %FileCheck %s
+// RUN: %target-run-simple-swift(-Xfrontend -disable-availability-checking -O) | %FileCheck %s
+
+// REQUIRES: executable_test
+
+// UNSUPPORTED: use_os_stdlib
+// UNSUPPORTED: back_deployment_runtime
+
+protocol Marked {
+  func announce()
+}
+extension Marked {
+  func announce() { print("\(Self.self) is Marked") }
+}
+
+struct ConcreteWrapper<Wrapped> {}
+extension ConcreteWrapper: Marked where Wrapped: Marked {}
+
+struct Hello<T: ~Copyable> {}
+extension Hello: Marked {}
+
+func makeWrapper<P>(wrapping _: P.Type) -> some Marked {
+    ConcreteWrapper<Hello<P>>()
+}
+
+do {
+  let markedVal = makeWrapper(wrapping: String.self)
+  markedVal.announce() // CHECK: ConcreteWrapper<Hello<String>> is Marked
+}